introduction to kidney and renal function Flashcards

1
Q

functions of the urinary system

A

excretion - removal of organic waste products from bodily fluids
elimination - discharge of waste into environment

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2
Q

essential renal functions

A
excretion 
of endogenous waste products 
of drugs and metabolites 
homeostasis 
water and electrolyte balance 
acid base balance 
regulation 
production of hormones eg erythropoietin and renin
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3
Q

renal dysfunction

A

reduction in renal excretory function (uraemia, aztoaemia, drug toxicity)
inability to maintain salt and water balance and acid base balance (metabolic consequences)
compromised hormone function (anaemia, hypertension etc)

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4
Q

how can kidneys fail (2 ways)

A

essential for life, if severe and untreated can = death
may be rapid (acute kidney injury, 10%) or may take months or typically years to develop chronic kidney disease (90%)
supplemented artificially by dialysis or transplant

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5
Q

where are the kidneys found

A

paired organs
posterior abdominal wall
behind peritoneum
on either side of vertebral column
erach kidney 120-170g, approx 11cm long, 6 cm wide, 3 cm thick
joined at medial side to renal artery and vein, nerves and ureter

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6
Q

organisation of the kidney

A

two main layers
cortex (outer, about 1.25 million nephrons) and medulla (inner, functional unit, responsible for urine formation and composition - pyramids drain into pelvis into ureters)

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7
Q

what is the nephron

A
basic functional unit 
dec with age 
5 distinct sections 
glomerulus (renal corpuscle)
proximal tubule (PT)
Loop of Henle (LOH)
Distal tubule (DT)
Collecting duct (CT)
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8
Q

what are the two types of nephrons

A

cortical and juxtamedullary

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9
Q

what are cortical nephrons

A

70-80%
located in cortex
short loop of hence into medulla

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10
Q

what are juxtamedullary nephrons

A

closer to medulla

loop of hence extends deep into renal pyramids

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11
Q

what is the blood supply to the kidney

A

receive 20% CO
required for energy consuming transport processes
enter renal artery branches and leaves via renal vein also branches before leaving

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12
Q

pathway of blood into kidneys

A
renal artery 
segmental
interlobar 
arcuate 
afferent arterioles 
interlobular 
to nephron (glomerulus to peritubular capillaries) to venules 
interlobular
arcuate
interlobar 
to renal vein
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13
Q

blood supply to nephrons

A

afferent in and efferent out
peritubular capillaries in cortical
peritubular capillaries at top to vasa recta

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14
Q

sympathetic supply to kidneys

A

postganglionic from sympathetic chain and fibres from coeliac ganglion
supplied arteries, afferent and efferent arterioles and granular cells
reduces blood supply to kidney during stress

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15
Q

parasympathetic supply to kidney

A

from vagus nerve (ganglion in hilum)
many control tone of efferent arterioles
may modify glomerular filtration rate and renal blood flow
controversial

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16
Q

main functions of the nephron

A

filtration of blood =filtrate
reabsorption of water, ions and organic nutrients from filtrate
secretion of waste into tubular fluid

17
Q

how do the nephrons work

A
transcellular transport (through cells)
paracellular transport (between cells)
18
Q

how does glomerular filtration occur

A

initial step in urine filtration
all small molecules filtered eg electrolytes, AAs, glucose, metabolic waste, some drugs and metabolites
cells and large molecules stay in blood eg RBCs, lipids, proteins, most drugs and metabolites

19
Q

how does tubular reabsorption occur

A

99% water, electrolytes and nutrients reabsorbed
some (Na+) via conc/electrochemical gradients
others co-transport (eg glucose and Na+)
water follows passively via osmosis (created by solute reuptake via aquaporins)
req ATP (Na+ reabsorption via Na+/K+ ATPase transporter)

20
Q

how does tubular secretion occur

A

some substances can’t be filtered - too big or protein binding
specialised pumps in PT can transport compounds from plasma into nephron for excretion
two kinds of pumps

21
Q

what are the two pumps involved in tubular secretion

A

for organic acids or drugs (eg uric acid, diuretics, antibiotics like penicillin)
for organic bases or drugs (eg creatinine, procainamide)